Controllable crossing gate arms have long been employed in various situations where a physical barrier is required to prevent traffic flow. These crossing gate arms are capable of pivoting upwardly out of the path of traffic in response to a command signal, thereby allowing the traffic to move freely when the barrier is not required. Typically, crossing gate arms are employed along roadways which cross railroad lines, as well as at highway toll booths and draw bridges in order to prevent passage of an automobile without payment of a desired toll or to allow a bridge to open.
Until the mid 1960""s, crossing gate arms found at railway grade crossings were severely damaged or destroyed if struck by a highway vehicle when the crossing gate arm was in a road blocking horizontal attitude. Subsequently, a breakaway system was developed which protects crossing gates from collision damage. This breakaway system incorporates a pivot pin and shear pins which enable the gate arm to swing out of the way of traffic in response to a collision with an automobile and drop free of the crossing arm support structure to the ground in a disabled position displaced from and approximately parallel to the roadway.
The pivot pin of the crossing arm assembly is connected between a crossing gate arm and its support structure. The support structure pivots the gate arm through a vertical arc between a road blocking horizontal attitude and an open road vertical attitude. The pivot pin and gate arm cooperate so that the gate arm is free to pivot through a defined horizontal arc about the pivot pin from the road blocking horizontal attitude to a release position parallel to the roadway when an automobile strikes the gate arm. During normal operation, this horizontal pivoting motion is inhibited by the use of shear pins which are mounted through the crossing arm support structure and the gate arm adapter, such that the gate arm remains in a fixed position relative to the support structure while the shear pins arm in place. These pins retain the position of the gate arm until hey are manually removed during maintenance of the gate arm, or until they are sheared from the support structure by the force of an automobile striking the gate arm.
Once an automobile strikes the gate arm and the gate arm swings to the release position, the gate arm adapter is arranged so that the adapter and connected gate arm freely fall away from the pivot pin and drop to the ground in the disabled position. This breakaway function allows the gate arm to fall away from the roadway as well as the railroad tracks, thus ensuring that the gate arm will not be a further hazard to traffic, and will not be further damaged once it has detached from the support structure. The gate arm typically is damaged by the automobile impact that prompted the breakaway function so that repair usually is required of the gate arm.
The breakaway system on the older gate arms, however, does not provide a means for effective maintenance of the gate arm. In particular, when the prior art gate arm requires maintenance, a maintenance person is usually required to lower the gate arm to the road blocking horizontal attitude which is almost impossible for one man to do because the counterweight must be lifted.
The following are solutions which have been patented to help solve the problem:
U.S. Pat. No. 4,090,685 discloses using a ratchet wrench to turn the motor to raise the counterweight.
U.S. Pat. No. 5,671,563 discloses a one man replaceable gate.
U.S. Pat. No. 5,852,350 discloses using a motor to raise the counterweight.
The last two patents do not apply to repairing crossing gates that have been in place for years.
The present invention is directed to a lever arm which is used to replace the crossing gate arm and then used to raise the counterweight so that the crossing gate arm can be replaced.